The Applicant already proposed a computer antitheft system (named "CATS" by the Applicant) as an antitheft mechanism of a car electronic device. The device may take a theft mode in which the device is inoperative so as to indirectly protect the device against robbery.
The theft mode is cancelled when a specific secret code normally consisting of four to six digits and inputted by an operator coincide with a secret code specifically assigned to the device. In this connection, such an antitheft mechanism in general includes a release means comprising a memory means for storing a particular code and a detector means for detecting coincidence between an inputted code and the particular code.
This arrangement, however, invites an inconvenience in the process of manufacturing the device itself or of mounting the finished device in a car. That is, every time when the device is tested or removed from the car for repair, a secret code unique to the device must be entered to cancel the theft mode and to establish its normal operative mode in order to reactivate the device.
This means that an operator in the manufacturing, mounting or testing process must know and confirm unique codes of individual devices, which causes a slow-down of the operation. Beside this, the unique code which should be maintained unknown becomes apparent to a third party, and this drops the value of the antitheft mechanism itself.